The device is intended to be used in an installation for manufacturing containers made of thermoplastic material and in particular polyethylene terephthalate (PET) by forming, in particular by blow molding or stretch blow molding, preforms. Such an installation makes it possible to produce containers on a very large scale at very high rates, for example greater than 85,000 bottles per hour.
According to a well-known technique, such containers are produced in two main steps. In a first step, molding is initiated by injection of a preform made of PET. This preform comprises an essentially tubular body that is closed at one of its axial ends, the opposite end being open by means of a neck. The neck has, right from this injection-molding operation, the definitive shape of the neck of the container. Generally, the neck of the container comprises a threading.
The preform generally comprises an annular support face that projects radially toward the outside relative to the rest of the body and that is oriented axially toward the closed end of the body. Such a support face is carried by, for example, an annular support collar that extends radially projecting toward the outside relative to the rest of the preform and that is arranged at the base of the neck.
There are installations in which the preforms, once injected, are directly passed on to the forming station, with each preform being transported individually.
However, in numerous cases, the preforms are manufactured by injection at a first location and are molded by blow molding to the definitive shape of the container at a second location in a specific manufacturing installation. Such a technology makes it possible to initiate the molding operation by blow molding as close as possible to the bottling site, with the injection operation able to be carried out at any location. Actually, it is relatively easy and inexpensive to transport preforms of reduced size, while transporting containers after blow molding has the drawback of being economically inefficient because of their very significant volume.
In the case where the injection station and the installation for manufacturing by forming are two totally independent machines, the preforms are generally delivered in bulk. The blow-molding station therefore uses a device for feeding preforms that is equipped with a device for aligning in a row and righting preforms. This invention relates to such a device.
An aligning and righting device comprising a centrifuge bowl was already proposed. The preforms are thrown in bulk onto a rotating platen that forms the bottom of the bowl. The preforms are then thrown off by the centrifugal force against a peripheral railing. A vertical space reserved between the railing and the rotating platen makes possible the passage of the bodies of the preforms while holding them by their collars. The preforms are thus aligned on the periphery of the bowl, with their main axis having an orientation that is essentially radial under the effect of the centrifugal force. The preforms thus have an axis that extends essentially orthogonally both in the direction of the gravity and the direction of movement of the preforms.
The preforms that are thus aligned and oriented in a similar manner are then driven toward a tangential outlet of the bowl under the effect of the movement of rotation of the rotating platen.
In this type of device, certain preforms are poorly aligned and even not aligned, with these two types of preforms being referred to below as non-aligned preforms. To make it possible to sort the non-aligned preforms from the correctly-aligned preforms, the known device comprises sorting means that are arranged upstream from a point of righting correctly-aligned preforms.
These sorting means consist of a deflector that allows the passage of correctly-aligned preforms toward an outlet of the centrifuge bowl while the non-aligned preforms are oriented in such a way as to go around the bowl again in hoping that they will be correctly aligned in their subsequent passage in the area of the sorting means.
However, the non-aligned preforms are not actively expelled from the row of correctly-aligned preforms. A blocking of a non-aligned preform across the row of correctly-aligned preforms can thus occur, thus causing a jam-up.
In addition, certain preforms are incorrectly aligned because they are nested together. The fact of distributing such nested preforms for going around again will not make it possible to disengage them. They will thus encumber the centrifuge bowl until they are manually expelled.